use std::collections::HashMap;
use std::ops::Range;
use std::rc::Rc;
use std::sync::Once;

use crate::parser::util::Property;
use crate::parser::util::PropertyMapError;
use crate::parser::util::PropertyParser;
use ariadne::Fmt;
use ariadne::Label;
use ariadne::Report;
use ariadne::ReportKind;
use crypto::digest::Digest;
use crypto::sha2::Sha512;
use graphviz_rust::cmd::Format;
use graphviz_rust::cmd::Layout;
use graphviz_rust::exec_dot;
use mlua::Function;
use mlua::Lua;
use regex::Captures;
use regex::Regex;

use crate::cache::cache::Cached;
use crate::cache::cache::CachedError;
use crate::compiler::compiler::Compiler;
use crate::compiler::compiler::Target;
use crate::document::document::Document;
use crate::document::element::ElemKind;
use crate::document::element::Element;
use crate::parser::parser::Parser;
use crate::parser::rule::RegexRule;
use crate::parser::source::Source;
use crate::parser::source::Token;
use crate::parser::util;

#[derive(Debug)]
struct Graphviz {
	pub location: Token,
	pub dot: String,
	pub layout: Layout,
	pub caption: Option<String>,
}

fn layout_from_str(value: &str) -> Result<Layout, String> {
	match value {
		"dot" => Ok(Layout::Dot),
		"neato" => Ok(Layout::Neato),
		"fdp" => Ok(Layout::Fdp),
		"sfdp" => Ok(Layout::Sfdp),
		"circo" => Ok(Layout::Circo),
		"twopi" => Ok(Layout::Twopi),
		"osage" => Ok(Layout::Asage), // typo  in graphviz_rust ?
		"patchwork" => Ok(Layout::Patchwork),
		_ => Err(format!("Unknown layout: {value}")),
	}
}

impl Graphviz {
	/// Renders dot to svg
	fn dot_to_svg(&self) -> Result<String, String> {
		print!("Rendering Graphviz `{}`... ", self.dot);

		let svg = match exec_dot(
			self.dot.clone(),
			vec![self.layout.into(), Format::Svg.into()],
		) {
			Ok(svg) => {
				let out = String::from_utf8_lossy(svg.as_slice());
				let split_at = out.find("<!-- Generated").unwrap(); // Remove svg header

				out.split_at(split_at).1.to_string()
			}
			Err(e) => return Err(format!("Unable to execute dot: {e}")),
		};
		println!("Done!");

		Ok(svg)
	}
}

impl Cached for Graphviz {
	type Key = String;
	type Value = String;

	fn sql_table() -> &'static str {
		"CREATE TABLE IF NOT EXISTS cached_dot (
				digest TEXT PRIMARY KEY,
				svg    BLOB NOT NULL);"
	}

	fn sql_get_query() -> &'static str { "SELECT svg FROM cached_dot WHERE digest = (?1)" }

	fn sql_insert_query() -> &'static str { "INSERT INTO cached_dot (digest, svg) VALUES (?1, ?2)" }

	fn key(&self) -> <Self as Cached>::Key {
		let mut hasher = Sha512::new();
		hasher.input((self.layout as usize).to_be_bytes().as_slice());
		hasher.input(self.dot.as_bytes());

		hasher.result_str()
	}
}

impl Element for Graphviz {
	fn location(&self) -> &Token { &self.location }

	fn kind(&self) -> ElemKind { ElemKind::Block }

	fn element_name(&self) -> &'static str { "Graphviz" }

	fn to_string(&self) -> String { format!("{self:#?}") }

	fn compile(&self, compiler: &Compiler, _document: &dyn Document) -> Result<String, String> {
		match compiler.target() {
			Target::HTML => {
				static CACHE_INIT: Once = Once::new();
				CACHE_INIT.call_once(|| {
					if let Some(mut con) = compiler.cache() {
						if let Err(e) = Graphviz::init(&mut con) {
							eprintln!("Unable to create cache table: {e}");
						}
					}
				});
				// TODO: Format svg in a div

				if let Some(mut con) = compiler.cache() {
					match self.cached(&mut con, |s| s.dot_to_svg()) {
						Ok(s) => Ok(s),
						Err(e) => match e {
							CachedError::SqlErr(e) => {
								Err(format!("Querying the cache failed: {e}"))
							}
							CachedError::GenErr(e) => Err(e),
						},
					}
				} else {
					match self.dot_to_svg() {
						Ok(svg) => Ok(svg),
						Err(e) => Err(e),
					}
				}
			}
			_ => todo!("Unimplemented"),
		}
	}
}

pub struct GraphRule {
	re: [Regex; 1],
	properties: PropertyParser,
}

impl GraphRule {
	pub fn new() -> Self {
		let mut props = HashMap::new();
		props.insert(
			"layout".to_string(),
			Property::new(
				true,
				"Graphviz layout engine see <https://graphviz.org/docs/layouts/>".to_string(),
				Some("dot".to_string()),
			),
		);
		Self {
			re: [Regex::new(
				r"\[graph\](?:\[((?:\\.|[^\[\]\\])*?)\])?(?:((?:\\.|[^\\\\])*?)\[/graph\])?",
			)
			.unwrap()],
			properties: PropertyParser::new(props),
		}
	}
}

impl RegexRule for GraphRule {
	fn name(&self) -> &'static str { "Graph" }

	fn regexes(&self) -> &[regex::Regex] { &self.re }

	fn on_regex_match(
		&self,
		_: usize,
		parser: &dyn Parser,
		document: &dyn Document,
		token: Token,
		matches: Captures,
	) -> Vec<Report<'_, (Rc<dyn Source>, Range<usize>)>> {
		let mut reports = vec![];

		let graph_content = match matches.get(2) {
			// Unterminated `[graph]`
			None => {
				reports.push(
					Report::build(ReportKind::Error, token.source(), token.start())
						.with_message("Unterminated Graph Code")
						.with_label(
							Label::new((token.source().clone(), token.range.clone()))
								.with_message(format!(
									"Missing terminating `{}` after first `{}`",
									"[/graph]".fg(parser.colors().info),
									"[graph]".fg(parser.colors().info)
								))
								.with_color(parser.colors().error),
						)
						.finish(),
				);
				return reports;
			}
			Some(content) => {
				let processed = util::process_escaped(
					'\\',
					"[/graph]",
					content.as_str().trim_start().trim_end(),
				);

				if processed.is_empty() {
					reports.push(
						Report::build(ReportKind::Error, token.source(), content.start())
							.with_message("Empty Graph Code")
							.with_label(
								Label::new((token.source().clone(), content.range()))
									.with_message("Graph code is empty")
									.with_color(parser.colors().error),
							)
							.finish(),
					);
					return reports;
				}
				processed
			}
		};

		// Properties
		let properties = match matches.get(1) {
			None => match self.properties.default() {
				Ok(properties) => properties,
				Err(e) => {
					reports.push(
						Report::build(ReportKind::Error, token.source(), token.start())
							.with_message("Invalid Graph")
							.with_label(
								Label::new((token.source().clone(), token.range.clone()))
									.with_message(format!("Graph is missing property: {e}"))
									.with_color(parser.colors().error),
							)
							.finish(),
					);
					return reports;
				}
			},
			Some(props) => {
				let processed =
					util::process_escaped('\\', "]", props.as_str().trim_start().trim_end());
				match self.properties.parse(processed.as_str()) {
					Err(e) => {
						reports.push(
							Report::build(ReportKind::Error, token.source(), props.start())
								.with_message("Invalid Graph Properties")
								.with_label(
									Label::new((token.source().clone(), props.range()))
										.with_message(e)
										.with_color(parser.colors().error),
								)
								.finish(),
						);
						return reports;
					}
					Ok(properties) => properties,
				}
			}
		};

		// Property "layout"
		let graph_layout = match properties.get("layout", |prop, value| {
			layout_from_str(value.as_str()).map_err(|e| (prop, e))
		}) {
			Ok((_prop, kind)) => kind,
			Err(e) => match e {
				PropertyMapError::ParseError((prop, err)) => {
					reports.push(
						Report::build(ReportKind::Error, token.source(), token.start())
							.with_message("Invalid Graph Property")
							.with_label(
								Label::new((token.source().clone(), token.range.clone()))
									.with_message(format!(
										"Property `layout: {}` cannot be converted: {}",
										prop.fg(parser.colors().info),
										err.fg(parser.colors().error)
									))
									.with_color(parser.colors().warning),
							)
							.finish(),
					);
					return reports;
				}
				PropertyMapError::NotFoundError(err) => {
					reports.push(
						Report::build(ReportKind::Error, token.source(), token.start())
							.with_message("Invalid Graph Property")
							.with_label(
								Label::new((
									token.source().clone(),
									token.start() + 1..token.end(),
								))
								.with_message(format!(
									"Property `{}` is missing",
									err.fg(parser.colors().info)
								))
								.with_color(parser.colors().warning),
							)
							.finish(),
					);
					return reports;
				}
			},
		};

		// TODO: Caption

		parser.push(
			document,
			Box::new(Graphviz {
				location: token,
				dot: graph_content,
				layout: graph_layout,
				caption: None,
			}),
		);

		reports
	}

	// TODO
	fn lua_bindings<'lua>(&self, _lua: &'lua Lua) -> Vec<(String, Function<'lua>)> { vec![] }
}